A. Field of the Invention
This invention relates generally to value printing systems and, more particularly, to a system wherein the accounting registers of the secure metering device are redundantly maintained within a plurality of non-volatile memory devices of different types, the devices being provided on a card or module adapted for insertion and removal from the system.
B. Prior Art
Value printing systems, such as a postage printing system, typically are comprised of a secure metering device for recording the values printed, a control device for controlling a printer, and the printer itself for applying indicia representative of the value to a document.
The secure metering device is typically comprised of registers, known as ascending and descending registers, which are utilized to record the values printed. Typically, the ascending register is incremented by the value printed while the descending register is decremented by the value. When the descending register has been so decremented to some minimum value, indicating that the funds originally allocated to the meter have been depleted, the metering device inhibits the further printing of indicia until the meter is "recharged", or resupplied with funds. As is well known, it is a requirement that a postage meter maintain an accurate and secure record of the value of the postage applied. The use of a non-volatile memory ensures that the postage accounting data stored therein will be accurately maintained even when the meter power is intentionally or unintentionally interrupted.
It has been known to utilize more than one non-volatile memory device within a postage meter in order to further ensure the security and accuracy of the postage accounting data, the data typically being redundantly maintained within each of the non-volatile memories. Illustrative of such a postage meter is a U.S. Pat. No. 4,566,106, issued on Jan. 21, 1986 to F. Check, Jr., and entitled "Electronic Postage
Meter Having Redundant Memory", said U.S. patent being assigned to the assignee of the present application Check teaches the use of redundant non-volatile random access memories controlled by a microprocessor system, the memories having separate groups of address and data lines to minimize identical errors in data stored therein. Also illustrative of a postage meter having redundant non-volatile memories is a copending application No. 643,219, filed Aug. 22, 1984, entitled "Non-Volatile Memory System With Real Time And Power Down Data Storage Capability For An Electronic Postage Meter". This copending application discloses a method and associated apparatus for increasing the reliability of the stored accounting data which reflects the transactions of an electronic postage meter, including the steps of and associated apparatus for providing a first non-volatile memory capable of storing accounting data which represents the postage meter transactions; updating the first non-volatile memory in real time for each postage transaction to provide a current record of the accounting data for each postage transaction on-the-fly; providing a second non-volatile memory capable of storing accounting data representing the postage meter transactions during a power down cycle of the postage meter; providing a volatile memory capable of storing accounting data which represents the postage meter transactions; updating the volatile memory in real time for each postage transaction to provide a current record of the accounting data for each postage transaction; and transferring the accounting data from the volatile memory to the second non-volatile memory during the power down cycle of the postage meter.
Although the aforementioned postage meters employing redundant non-volatile memories are well suited for their intended applications, a problem arises when it is desired to physically separate the accounting registers and, hence, the non-volatile memories, from the postage meter enclosure For instance, it may be desireable to provide the accounting registers on a card or module adapted for insertion and removal from the postage meter system in order to provide a postage meter which does not require a complex mechanical or electrical security system. It may further be desireable to provide such a card or module in order to enable the postage funds within the meter to be periodically recharged.
As may be appreciated, non-volatile memory devices which are contained within a module or card enclosure adapted for removal from a postage meter system may be subjected to severe electrical and mechanical stresses. For example, the card may be inadvertently dropped upon a hard surface, or the card may be exposed to extremes of temperature and humidity. The devices provided with the card may also be exposed to static electric discharge. Furthermore, the card or module may be inadvertently inserted or withdrawn from a postage meter system which is in an operational condition, thereby possibly exposing the memory devices within to fluctuations upon their respective power or data busses. Thus, it may be seen that providing the accounting registers external to the meter may place extreme environmental, mechanical and electrical stresses upon the non-volatile memories containing the postal accounting registers.
It is, however, a desireable goal to so provide the registers external to the meter in that such a postage meter may be conveniently and rapidly recharged with postal funds.
As is well known, in order to recharge many postage meters of the prior art it was often necessary to physically convey the entire system, including the printer, to a postal facility or some other similar facility. Such a recharging scheme is obviously disadvantageous in that the system was required to be removed from service during the recharging procedure. This requirement was due partially to the fact that the metering device and the printer were integrated into an assembly of unitary construction, such an assembly typically having a complex mechanical mechanism to couple the metering device to the printer in order to prevent the use of the printer apart from the meter.
In response to the aforementioned disadvantage of requiring the removal of the system to a recharging facility, it has also been known in the prior art to provide for the recharging the metering device locally, that is, without the physical removal of the system.
Illustrative of one such local recharging technique, wherein the meter is recharged by the use of a punched card or a data entry medium purchased at a postal or some other facility and thereafter inserted into the meter to transfer the amount of funds appearing on the card or coupon into the meter, are a U.S. Pat. No. 3,194,946, issued on July 13, 1965 to Jacob Rabinow, entitled "Postage Meter Set by Cards", and the following Luther G. Simjian U.S. Pat. Nos. 4,218,011, issued Aug. 19, 1981, entitled "Coupon Controlled Metering Device", 4,222,518 issued Sept. 16, 1980, entitled "Metering System", 4,258,252, issued on Mar. 24, 1981, entitled "Check Controlled Metering Device", and 4,268,817, issued May 19, 1981, entitled "Check Controlled Metering Device." Also illustrative of this recharging technique is a copending application No. 108,261, filed Dec. 28, 1978, to Check Jr. et al, entitled "An Electronic Postage Meter System Settable By Means Of A Remotely Generated Input Device".
While postage printing systems constructed in accordance with the aforementioned U.S. patents do provide a means for locally recharging the metering device, the use of such systems are disadvantageous in other respects. One such disadvantage is that the secure accounting registers of the metering device are still contained within the system, thereby necessitating the use of the aforementioned complex mechanical mechanism to securely couple the meter to the printer. Another disadvantage of such prior art systems is that the overall system cost may be higher due to the requirement of providing a suitable punched card or coupon reading and validating device within the system.
It has also been known in the prior art to provide for the local recharging of the metering device by means of a data link to a central station or registering device. Illustrative of this recharging technique are two Luther G. Simjian U.S. Pat. Nos. 3,255,439, issued on June 7, 1966, entitled "Postage Metering System" and 3,428,948, issued on Feb. 18, 1969, entitled "Postage Metering System" and a U.S. Pat. No. 3,596,247, issued on July 27, 1971, to A. Eckert entitled "Automatic Register Setting Apparatus", and a U.S. Pat. No. 4,097,923 to Eckert et al, issued on June 27, 1978, entitled "Remote Postage Meter Charging System Using An Advanced Microcomputerized Postage Meter", said last two U.S. patents assigned to the assignee of the present application.
While postage printing systems constructed in accordance with the aforementioned U.S. patents do also provide a technique for locally recharging the metering device from a remote location, they suffer from similar disadvantages as those beforementioned. Those disadvantages are the inclusion of the meter accounting registers within the system, thereby requiring the securing of the entire system, and the added cost and complexity of providing within the system a suitable data link communications means.
In addition, these systems suffer from an additional disadvantage in that if the data link or the central station, which may be a computer system, malfunctions, the postal printing system may be required to remain out of service for an extended period of time, or until a time that the malfunction is corrected and the metering device can be recharged with funds.
It is therefore a primary objective of the present invention to provide a postal mailing system which may be recharged with postal funds without requiring the removal of the system to a remote recharging facility.
It is also a primary objective of the present invention to provide a postal mailing system wherein the secured postage meter accounting registers are maintained external to and separable from the system, thereby eliminating the requirement of mechanically securing the metering device and the printer.
It is also a primary objective of the present invention to provide a postal mailing system wherein the external postage meter accounting registers are redundantly maintained within two separate types of non-volatile storage devices, thereby providing an even greater degree of security for the postage meter accounting data.
It is also a primary objective of the present invention to provide a postal mailing system wherein the external postage meter accounting registers are contained within a low cost credit card-like enclosure which may be readily transported and inserted within the postal mailing system.